Breastfeeding, weaning, and dietary patterns in the east Qinghai-Tibet Plateau, China during Han and Jin Periods by stable isotope analysis

Breastfeeding and weaning represent critical phases in infant growth and development, offering valuable insights into early life conditions and the nutritional status of ancient populations. These practices significantly influenced population health, fertility rates, and, by extension, the stability and development of social economies. In recent years, bioarchaeological research has increasingly focused extensively on breastfeeding and weaning practices in ancient populations. However, limited attention has been paid to such practices during Han and Jin periods in the eastern Qinghai-Tibet Plateau. This study investigates the dietary structure and breastfeeding-weaning patterns of the ancient inhabitants of the Taojiazhai Cemetery in Xining, Qinghai, dating to Han and Jin periods (approximately 206–352 CE). Stable isotope analysis was conducted on 8 skeletal samples and 98 sequential dentin samples. The results indicate that the Taojiazhai population’s diet consisted of a mixture of C₃ and C₄ plants, with a predominant reliance on C₃ plants, supplemented by varying amounts of animal protein. Most residents were weaned between 2.6 and 3.5 years of age, with males generally weaned later than females. In terms of feeding strategies, males consumed slightly more animal protein and C₄ foods than females during the weaning period, and after weaning, showed a dietary pattern featuring greater intake of animal protein and C₃-based foods. When interpreted in conjunction with the subsistence economy, historical background, funerary objects, and paleopathology, these findings also shed light on the rise of male-biased inequality in access to dietary resources, patterns of daily life, and social hierarchy.